Our long-term goal is to identify ensembles of genes that undergo altered transcriptional regulation during the early stages of the development of some forms of glaucoma, and to identify in the human population at large polymorphisms in such genes that may predispose individuals who harbor them to the development of the disease. Glaucoma is the leading treatable cause of irreversible blindness worldwide and affects more than 60 million people. The genetic factors that predispose to glaucoma in the population at large remain, however, largely unknown. Previously, we established Drosophila melanogaster as a model system for studies of the effects of the human glaucoma-associated "trabecular meshwork inducible glucocorticoid response" protein (also known as myocilin; TIGR/MYOC) and identified transcripts that are up- or down-regulated when TIGR/MYOC is overexpressed in the Drosophila eye. Drosophila remains unsurpassed as a versatile genetic model, which can be used as a rapid gene discovery system, in which transcriptional profiling can identify genes that undergo altered regulation when candidate glaucoma genes are expressed in the Drosophila eye. After identifying human orthologues of such genes we can ask which of them show alterations in their expression in perfused post mortem human eyes when TIGR/MYOC (or other candidate glaucoma genes) are introduced via an adenovirus. We will then investigate whether polymorphisms in candidate genes implicated via this two-step screen are linked to the incidence of glaucoma in a West-African human population. The specific aims of this proposal are to: (l)'Assess the ocular phenotypes of flies with targeted overexpression of TIGR/MYOC mutants and targeted RNAi mediated downregulation of TIGR/MYOC-modulated genes and perform analyses and comparisons of transcriptional alterations among transgenic strains; (2) Assess whether human homologues of Drosophila genes, discovered previously and in Specific Aim 1, are up- or down-regulated in perfused post mortem human eyes subjected to overexpression of TIGR/MYOC, or of other new candidate glaucoma genes; and, (3) Evaluate whether polymorphisms in new candidate glaucoma genes are associated with ocular hypertension and the incidence of glaucoma in a West-African population with high incidence of the disease. These experiments represent a novel strategy for candidate disease susceptibility gene discovery and will lay the foundation for future large scale genomic SNP studies to identify the full complement of genes that may convey susceptibility to glaucoma.